Chapter 15 - Ears Flashcards
Binaural interaction at the level of the brain stem permits…
identification and location of the direction of the sound
The labyrinth of the inner ear is responsible for maintaining the body’s…
equilibrium
If the tympanic membrane has white dense areas, the examiner suspects…
scarring from recurrent ear infections
the pars flaccida
The small, slack, superior section of the tympanic membrane
annulus
the outer fibrous rim of the drum
Lymphatic drainage of the external ear flows to which nodes?
parotid, mastoid, and superficial cervical nodes
The middle ear has three functions:
(1) it conducts sound vibrations from the outer ear to the central hearing apparatus in the inner ear
(2) it protects the inner ear by reducing the amplitude of loud sounds
(3) its eustachian tube allows equalization of air pressure on each side of the tympanic membrane so that the membrane does not rupture (e.g., during altitude changes in an airplane)
bony labyrinth
holds the sensory organs for equilibrium and hearing
- Vestibule
- Semicircular Canals
- Cochlea
Vestibule & Semicircular Canals
compose the vestibular apparatus
Cochlea
contains the central hearing apparatus
The function of hearing involves the auditory system at three levels:
peripheral, brainstem, and cerebral cortex
Peripheral level of hearing
the ear transmits sound and converts its vibrations into electrical impulses, which can be analyzed by the brain.
Brainstem level of hearing
binaural interaction, which permits locating the direction of a sound in space as well as identifying the sound
Cerebral cortex level of hearing
interpret the meaning of the sound and begin the appropriate response.
organ of Corti
the sensory organ of hearing
What are the 2 pathways of hearing?
Air Conduction (AC) - most efficient Bone Conduction (BC)
*vibration are transmitted to inner ear TO cranial nerve VIII
2 types of hearing loss:
Conductive & Sensorineural
Conductive hearing loss
involves a mechanical dysfunction of the external or middle ear.
partial loss because the person is able to hear if the sound amplitude is increased enough to reach normal nerve elements in the inner ear.
may be caused by: impacted cerumen, foreign bodies, a perforated tympanic membrane, pus or serum in the middle ear, and otosclerosis (a decrease in mobility of the ossicles).
sensorineural hearing loss
signifies pathology of the inner ear, cranial nerve VIII, or the auditory areas of the cerebral cortex.
increase in amplitude may not enable the person to understand words.
may be caused by presbycusis
presbycusis
a gradual nerve degeneration that occurs with aging, and by ototoxic drugs, which affect the hair cells in the cochlea.
Otosclerosis
common cause of conductive hearing loss in young adults between the ages of 20 and 40 years.
gradual hardening that causes the footplate of the stapes to become fixed in the oval window, impeding the transmission of sound and causing progressive deafness.
Otitis media, or OM (middle ear infection)
occurs because of obstruction of the eustachian tube or passage of nasopharyngeal secretions into the middle ear
Cerumen is genetically determined to be of two major types:
(1) dry cerumen, which is gray and flaky and frequently forms a thin mass in the ear canal; and
(2) wet cerumen, which is honey brown to dark brown and moist.
Chromosome 16 holds one gene trait determining the wet or dry phenotype.
The wet cerumen phenotype occurs more often in Caucasians and African Americans
dry cerumen is more frequent in Asians and American Indians.
The presence and composition of cerumen are not related to poor hygiene. Take caution to avoid mistaking the flaky, dry cerumen for eczematous lesions.
Otalgia
(earache) may be directly due to ear disease or may be referred pain from a problem in teeth or oropharynx.
Otorrhea
(discharge) suggests infected canal or perforated eardrum
xternal otitis
purulent, sanguineous, or watery discharge
Acute otitis media with perforation
purulent discharge.
Cholesteatoma
dirty yellow/gray discharge, foul odor.
Recruitment
a marked loss when speech is at low intensity, but sound actually becomes painful when speaker repeats in a loud voice.
Microtia
ears smaller than 4 cm vertically
macrotia
ears larger than 10 cm
Test Hearing Acuity: Audiometer
Battery powered machine that emits sounds. When patient hears sound, raise a hand/finger to signify. Rate results
Test Hearing Acuity: Whispered Voice Test
Test one ear at a time while masking hearing in the other ear to prevent sound transmission around the head.
place one finger on the tragus and rapidly pushing it in and out of the auditory meatus. Shield your lips so the person cannot compensate for a hearing loss (consciously or unconsciously) by lip reading or using the “good” ear. With your head 1 to 2ft from the person’s ear, exhale and whisper slowly a set of 3 random numbers and letters, such as “5, B, 6.”
Test Hearing Acuity: Tuning Fork Test
Tuning fork tests measure hearing by air conduction (AC) or by bone conduction (BC), in which the sound vibrates through the cranial bones to the inner ear.
THE VESTIBULAR APPARATUS: The Romberg test
assesses the ability of the vestibular apparatus in the inner ear to help maintain standing balance. Because the Romberg test also assesses intactness of the cerebellum and proprioception
Frostbite
Reddish blue discoloration and swelling of auricle after exposure to extreme cold. Vesicles or bullae may develop, the person feels pain and tenderness, and ear necrosis may ensue.
Swimmer’s Ear
(Otitis Externa) An infection of the outer ear, with severe painful movement of the pinna and tragus, redness and swelling of pinna and canal, scanty purulent discharge, scaling, itching, fever, and enlarged tender regional lymph nodes. Swimming causes canal to become waterlogged and swell; skinfolds are set up for infection.
Prevent by using rubbing alcohol or 2% acetic acid eardrops after every swim.
Cellulitis
Inflammation of loose, subcutaneous connective tissue. Shows as thickening and induration of auricle with distorted contours.
Tophi
Small, whitish yellow, hard, nontender nodules in or near helix or antihelix; contain greasy, chalky material of uric acid crystals and are a sign of gout.
Exostosis
More common than osteoma. Small, bony hard, rounded nodules of hypertrophic bone, covered with normal epithelium. They arise near the drum but usually do not obstruct the view of the drum. They are usually multiple and bilateral. They may occur more frequently in cold-water swimmers.
no treatment, although it may cause accumulation of cerumen, which blocks the canal.
Furuncle
Exquisitely painful, reddened, infected hair follicle. It may occur on the tragus on the cartilaginous part of ear canal. Regional lymphadenopathy often accompanies a furuncle.
Polyp
Arises in canal from granulomatous or mucosal tissue; redder than surrounding skin and bleeds easily; bathed in foul, purulent discharge; indicates chronic ear disease. Benign, but refer for excision.
